Mohasco Corp., the nation's largest interior furnishings company, announced yesterday that it plans to move its corporate headquarters to Fairfax County in late 1987.

The manufacturer of upholstered furniture and Mohawk carpets decided to move its base from Amsterdam, N.Y. -- where it has operated for the past 107 years -- so it can be closer to its manufacturing operations in the South.

With annual revenue last year of $716.3 million, Mohasco would be the area's 14th-largest firm, just behind Washington Gas Light Co.

"The decision to relocate Mohasco from our Upstate New York roots was difficult to make," said Mohasco's chairman, Herbert J. Broner. "However, since nearly all of our major operations are in the southern part of the country, being closer to them will signficantly improve communications, reduce travel time and expense and enable our corporate and divisional management teams to work together more effectively."

The headquarters will be just west of the Fair Oaks Mall between Rte. 50 and I-66. The purchase of the six-acre site from Fair Lakes Development Corp. -- a Hazel Peterson Co. affiliate -- and the construction of the 60,000-square-foot office building will be financed by a $7 million Fairfax County tax-exempt industrial revenue bond, already approved by the county. Cort Furniture Rental Divison, a subsidiary of Mohasco with headquarters in Fairfax, will relocate to the new building when it is completed.

In total, about 100 employes will be transferred to the headquarters; about half will come from Upstate New York.

The manufacturing operations will remain in the South.

Broner said the relocation project will result in a one-time write-off of about $1.9 million.